634934 – dev-lang/python:3.6: BLAKE2 w/ pure SSE2 is prohibitively slow (compared to ref)

Bug 634934 - dev-lang/python:3.6: BLAKE2 w/ pure SSE2 is prohibitively slow (compared to ref)

Summary: dev-lang/python:3.6: BLAKE2 w/ pure SSE2 is prohibitively slow (compared to ref)

Status:	RESOLVED FIXED

Alias:	None

Product:	Gentoo Linux
Classification:	Unclassified
Component:	Current packages (show other bugs)
Hardware:	All Linux

Importance:	Normal normal (vote)
Assignee:	Python Gentoo Team

URL:	https://bugs.python.org/issue31834
Whiteboard:
Keywords:

Depends on:
Blocks:

Reported:	2017-10-21 08:05 UTC by Michał Górny
Modified:	2018-11-19 05:46 UTC (History)
CC List:	0 users

See Also:	https://github.com/python/cpython/pull/4066
Package list:
Runtime testing required:	---

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Description Michał Górny archtester

2017-10-21 08:05:34 UTC

As explained on the upstream bug, the pure SSE2 implementation of BLAKE2 is always slower than the reference implementation. On Athlon64, it's even 2.5 times slower.

It might be reasonable to disable the intrinsic variant if the CPU doesn't support at least SSSE3 (which is the lowest supported optimization that may make the code faster). I suppose we should use -march= for that check since that's what the upstream code uses.

Comment 1 Virgil Dupras (RETIRED) gentoo-dev

2018-11-18 21:44:11 UTC

mgorny, from what I see, your PR was merged upstream (congratulations!) a while ago already and is present in python 3.7.0. Can we consider this bug fixed or do we want to backport this to 3.6?

Comment 2 Michał Górny archtester

2018-11-19 05:46:33 UTC

I suppose nobody reported a bug so far so we should be good.